General factors that affect medication response in infants and children:
Pharmacokinetics in Children and Infants
Things to consider: •Immaturity of organ systems is the most significant factor that affects medication response in infants and children •More sensitive to medications •Individual response to medication more variable •Absorption •Distribution •Metabolism •Excretion •Concentration
Let’s Look at Absorption: Oral Route –Most absorption occurs in small intestine –Factors affecting absorption: »Gastric Acidity »Gastric Emptying »Gastric Motility »Gastric Enzyme Activity •Do not crush –sustained-release medications –enteric coated medications
IM ·Less muscle and erratic blood flow IV ·Dependent on adequate perfusion
Topical Infants •Thinner skin •Greater BSA/Wt ratio
Children •Skin pH varies with age •More prone to irritation Let’s Look at Distribution: •Differences in body fluid •Differences in fat percentages •Differences in proteins •Blood-brain barrier •More body fluid = higher dilution of H20 soluble meds = require higher doses of H20 soluble meds •More fat = more fat soluble medication needed •Decreased plasma proteins = less of certain medications needed to reach therapeutic effect •Less selective BBB = increased distribution of meds into CNS •Immature nervous system = paradoxical effects from certain medications Let’s Look at Metabolism: •Liver is the primary site for drug metabolism –Preemie and newborn •decreased ability to metabolize the dose –Toddlers •increased capacity to metabolize the dose (may need more pain medications)
Let’s Look at Excretion: Main site of drug excretion is through the kidneys –Renal system immature at birth –Cannot filter medications to be excreted •Medications may circulate longer and reach toxic levels –Dehydration •Decreased ability to excrete medications •Can seriously effect drug levels () Let’s Look at Concentration: •Maximum effectiveness of medication
Keep serum levels within a safe therapeutic range
Pharmacokinetics in Children and Infants
Things to consider:
• Immaturity of organ systems is the most significant factor that affects medication response in infants and children
• More sensitive to medications
• Individual response to medication more variable
• Absorption
• Distribution
• Metabolism
• Excretion
• Concentration
Let’s Look at Absorption:
Oral Route
– Most absorption occurs in small intestine
– Factors affecting absorption:
» Gastric Acidity
» Gastric Emptying
» Gastric Motility
» Gastric Enzyme Activity
• Do not crush
– sustained-release medications
– enteric coated medications
IM
· Less muscle and erratic blood flow
IV
· Dependent on adequate perfusion
Topical
Infants
• Thinner skin
• Greater BSA/Wt ratio
Children
• Skin pH varies with age
• More prone to irritation
Let’s Look at Distribution:
• Differences in body fluid
• Differences in fat percentages
• Differences in proteins
• Blood-brain barrier
• More body fluid = higher dilution of H20 soluble meds = require higher doses of H20 soluble meds
• More fat = more fat soluble medication needed
• Decreased plasma proteins = less of certain medications needed to reach therapeutic effect
• Less selective BBB = increased distribution of meds into CNS
• Immature nervous system = paradoxical effects from certain medications
Let’s Look at Metabolism:
• Liver is the primary site for drug metabolism
– Preemie and newborn
• decreased ability to metabolize the dose
– Toddlers
• increased capacity to metabolize the dose (may need more pain medications)
Let’s Look at Excretion:
Main site of drug excretion is through the kidneys
– Renal system immature at birth
– Cannot filter medications to be excreted
• Medications may circulate longer and reach toxic levels
– Dehydration
• Decreased ability to excrete medications
• Can seriously effect drug levels ()
Let’s Look at Concentration:
• Maximum effectiveness of medication
Keep serum levels within a safe therapeutic range
• Peak Level
• Trough Level